1. The Field of the Invention
The present invention pertains to the technical field of lifting apparatuses, and particularly relates to a boom-adjustable horizontal hydraulic jack with a pull-lock mechanism, which is an improvement to the boom structure of the existing horizontal hydraulic jacks.
2. The Relevant Technology
At present, the horizontal hydraulic jacks commonly seen in the market mainly comprise a chassis, a hydraulic assembly, a boom assembly, a link rod, and a press handle, wherein, the boom assembly comprises a boom and a bearer arranged on the boom, one end of the link rod is pivotably connected with the chassis, and the other end of the link rod is pivotably connected with the bearer of the boom assembly. During the lifting process, by pressing the press handle repeatedly, the hydraulic assembly drives the boom assembly to lift up, and finally the bearer on the boom jacks up the weight. The structure described above has the following drawback: for the same kind of horizontal hydraulic jacks, i.e., when the parameters such as oil pressure and stroke are fixed, both the lifting height and the load capacity thereof will be fixed and cannot be changed; therefore, such a horizontal hydraulic jack has single function and limited applicability. To overcome the drawback described above, a new kind of horizontal hydraulic jack has emerged in the market, in which the lifting height and load capacity at the lowest position can be changed effectively by adjusting the length of the boom and the length of the link rod under the condition with the same parameters. For example, in the Chinese Patent Application, submitted by the present applicant on Sep. 16, 2009, with the Publication No. CN101691194A, entitled “Adjustable Horizontal Hydraulic Jack”, the boom can be lifted up in folded and normal position statuses, and the switch between the two statuses is accomplished by means of a fixing pin. Such a structure is simple, but the switching operation is troublesome.
In view of the above drawbacks, the applicant has tried and found a solution to solve the above-mentioned technical problems. The technical scheme to be described below is right created in such a background.